1895 THE MICROSCOPE. 59 



then reduce the adjustment until best definition be se- 

 cured or be proven to be impracticable ; as the lens when 

 set for a minimum depth might rest upon the cover, 

 while the object was still out of sight directly below the 

 field of view. It is folly for any but the experts to at- 

 tempt such work, and they will generally be wise enough 

 to prefer doing it over their own slides. — P. M. Club. 



What are the Bacillariaceae. 



By ARTHUR M. EDWARDS, M. D. 



NEWARK, N. J. 



As I have proposed to change the name Diatomacese to 

 BacillariacesB I will say why that change should be made. 

 The name is not a new one. To explain why it is pro- 

 posed to renew it, I quote from the Rev. Eugene O' 

 Meara in his Recent Researches on the DiatomacesB (Vol. 

 XII, n. s. of the Quarterly Journal of Microscopical 

 Science, 1872, page 240, reprinted from the Journal of 

 Botany, March and May, 1872.) Therein he says : " The 

 name Diatomacese has been used by nearly all of the 

 recent authors to designate this group. Rabenhorst, in 

 his more recent work, has adopted the name Diatomo- 

 phycsB, but in his former treatise used that of Diatoma- 

 cese, *' die Susswasser Diatomaceen ; " and in this he has 

 been followed by Gmelin, Heiberg, Shumann, Cleve and 

 Suringar. Dr. Pfitzer, however, mentions that the name 

 Bacillariacse should be substituted, the genus Bacillaria 

 having been established by De Candolle in 1805 ; and 

 some of the older writers on the subjects have used this 

 designation. It may be deemed inconvenient now to 

 abandon the name of the group which has been so gen- 

 erally adopted, but on technical grounds, Dr. Pfitzer's 

 view is undoubtly correct." 



So it happens that the organisms which were called 

 Diatomacese are now and should be called Bacillariaceae. 

 Popular observers who are not students may still call 



